B.S. Western Michigan University

M.S. Mayo Graduate School

Ph.D. Western Michigan University

Molecular Biology Program

Melanoma, Carcinoma, Non-Small-Cell Lung, Molecular Targets

Research

My research program has four major areas of focus: (1) Utilizing our RCAS/TVA model
in order to identify novel drivers of melanoma (e.g., NF-1, KIT, RAC1, PDGFRA), identify
resistance mechanisms, and to develop more effective therapeutic strategies. (2)
Developing CRISPR/Homology Directed Repair (HDR) for in vivo cancer and disease modeling. (3) Characterizing immune checkpoint ligands and evaluating
their role in immune evasion in melanoma with long term goals of developing therapeutic
agents. (4) Oncolytic Immunotherapy, focusing on developing/evaluating novel oncolytic
viruses in combination with immune checkpoint blockade in vivo.

1) RCAS-TVA model. We are currently evaluating a role for RAC1P29S in melanoma initiation and progression in BRAF or NRAS driven melanomas. Preliminary
data suggests that RAC1 is insufficient as a melanoma driver in the context of Cdkn2a and/or Pten loss, but may enhance metastatic progression of BRAF driven tumors. We are assessing
a role for RAC1 in promoting metastatic dissemination in our NRAS and Nf-1 melanomas
as these alterations co-occur in patients (13-14%). Utilizing in vivo CRISPR targeting Nf-1 (exon 2 or 4) we were successful in inducing tumors in our mouse model in the context
of Cdkn2aand/or Pten loss with high penetrance. We are expanding this model to assess pharmacologic and
immunotherapeutic intervention strategies.

2) CRISPR/HDR modeling. We have developed a novel method for single vector CRISPR mediated homology directed
repair (HDR) that has high potential in developing novel disease models and gene therapy
applications. As proof of principle, we have evaluated the ability of our CRISPR/Cas9-HDR
vector to correct altered GFP (possessing an early termination codon) in vitro. We observed a 23% repair rate with our single vector design comparable to current
state of the art approaches requiring multiple factors including a ssDNA oligo (17.7%).
We have also observed similar results with another CRISPR nuclease hAsCpf1 (15%).
We are in the process of applying our technology to developing preclinical models
of cancer (e.g., NSCLC, melanoma) and correcting monogenic diseases (e.g., CTFR).

3) Evaluating B7-H3 and B7-H4. We have observed that each of these immune checkpoint ligands is vital for immune
evasion in a murine syngeneic tumor model where loss of either (via CRISPR) results
in a 0% (B7-H3, 0/51 - B7-H4 0/37) take rate compared to parental melanoma cells with
a 60% take rate in these immune competent mice. We are characterizing their role in
immune evasion and utilizing novel methods to identify their receptors on CD8+ T cells.
We have also begun to develop antibodies that block the interaction of these immune
checkpoint ligands with their receptors in order to block immunosuppressive signaling.

4) Oncolytic immunotherapy. We have developed several novel oncolytic viruses and are evaluating them in several
preclinical cancer models. These are wild type RNA viruses that utilize cellular receptors
often overexpressed on many tumor types. Therefore, their tropism is largely limited
to specific tumor cells enhancing viral infection and spread while limiting toxicity.
We are evaluating these as single agents and in combination with immune checkpoint
blockade. We are generating modified viruses with expanded tropism by altering capsid
genes. We are also developing replication competent viruses encoding small immunomodulatory
factors that may enhance host antitumor immunity. In addition, in collaboration with
Dr Robert Andtbacka we are evaluating longitudinal patient samples treated with oncolytic
viruses (HF10, CVA21) in order to identify biomarkers of response and/or resistance.